cjs-to-es6

by nolanlawson

nolanlawson / cjs-to-es6

CLI to convert CommonJS to ES6 modules (UNMAINTAINED)

207 Stars 17 Forks Last release: Not found Apache License 2.0 30 Commits 4 Releases

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cjs-to-es6 (UNMAINTAINED)

CLI to convert JavaScript files from CommonJS to ES6 modules (aka ES2015 modules, aka JavaScript modules, aka hipster

require()
).

This tool uses 5to6-codemod under the hood. It's basically just a thin convenience wrapper, which can process multiple files and convert both

import
s and
export
s.

Note that the process isn't foolproof, so you may have to manually tweak some things. But it can usually get you ~95% of the way there. See migrating below for some tips.

Usage

Install it:

npm install -g cjs-to-es6

Then run it:

cjs-to-es6 [ --verbose ] files/directories...

Examples:

cjs-to-es6 index.js             # convert a single file
cjs-to-es6 lib/                 # convert all files in a directory
cjs-to-es6 foo.js bar.js lib/   # convert many files/directories

All files are modified in-place.

Example input and output

In comes CommonJS:

var flimshaw = require('flimshaw');
var twentyEightSkidoo = require('twenty-eight').skidoo;

exports.flubTheDub = 'flubTheDub'; module.exports = 'zings';

Out goes ES6 modules:

import flimshaw from 'flimshaw';
import {skidoo as twentyEightSkidoo} from 'twenty-eight';

export let flubTheDub = 'flubTheDub'; export default 'zings';

Migrating from CommonJS to ES6 modules

Not all uses of CommonJS have a 1-to-1 equivalent in ES6 modules. So you might have to correct some errors manually.

Use

--verbose
to get detailed output, or follow these general tips:

export
s must be at the top level

This is invalid:

if (clownShoes) {
  export default new Clown();
} else {
  export default new RespectableGentleman();
}

Instead do:

var result = clownShoes ? new Clown() : new RespectableGentleman();
export default result;

import
s also have to be at the top level

This is invalid:

try {
  import MysteryModule from 'mystery-module';
} catch (err) {
  console.log("It's a mystery!");
}

There is no equivalent for this

try
/
catch
pattern in ES6 modules.

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